This invention relates to a bookbinding apparatus for forming a booklet by gluing a sheet bundle with a cover sheet and an image forming system including the bookbinding apparatus.
Unexamined Japanese Patent Application Publication No. 2004-209869 discloses an bookbinding apparatus for simply conducting a wrapping bookbinding process by covering a bundle of a plurality of sheets (it is called book sheets) onto which an image has been formed by a copier and a printer, in a U-shape by a cover sheet, and gluing the cover sheet onto the spine of the sheet bundle.
An example of a book formed by a bookbinding apparatus will be illustrated in FIGS. 10(a) to 10(c). FIG. 10(a) illustrates a bundle of book sheets and cover sheet S2. FIG. 10(b) illustrates a situation where adhesive (glue) is coated on the spine of the bundle of book body sheets S1 and the cover sheet S2 is adhered thereto. FIG. 10(b) illustrates where the cover sheet S2 is not folded. FIG. 10(c) illustrates a situation where the cover sheet S2 has been folded. S3 is structured by the book body sheets S1 of a plurality of sheets and the cover sheet S2 so that the cover sheet S2 covers the book body sheets S1 in a U-shape style. The style of the book like S3 is called a wrapping book.
The coating amount of adhesive when coating the adhesive onto the spine of the book body sheets S1 is a key management point, which affects the finishing. In case when the coating amount is less, adhesive force is insufficient. In case when the coating amount is too much, the adhesive spreads around the spine. As a result, due to the excessive adhesive, the quality of the book becomes inferior.
In order to solve this problem, Unexamined Japanese Patent Application Publication No. 2000-168265 discloses a bookbinding apparatus for adjusting a quantity of adhesive by structuring the bookbinding apparatus to provide a scraping roller for scrapping coated adhesive together with a coating roller for coating the adhesive and to change the height of the scraping roller to adjust the adhesive to be scraped corresponding to the thickness of the sheet bundle.
However, in the bookbinding apparatus disclosed in Unexamined Japanese Patent Application Publication No. 2000-168265, there is an effect that the scraping roller scrapes adhesive excessively coated by a coating roller. However there is no effect that the scraping roller applies the adhesive. Thus, in case when the coating amount of the adhesive by the coating roller is small, unevenness of the adhesive to the spine of the sheet bundle occurs. As a result, quality inferior, such as, wrinkles appear on the spine of the sheet bundle.